1. Field of the Invention
The present invention relates to an apparatus for classifying a vehicle occupant which classifies a vehicle occupant sitting in the seat of a vehicle in order to deploy an airbag in accordance with an occupant's age equal to or greater than certain age or certain physical requirements.
2. Description of the Related Art
Recently, in many cases, an airbag is installed for a passenger seat, as well as a driver seat, for the safety of vehicle occupants.
Such an airbag is deployed when a collision between vehicles occurs, thus protecting vehicle occupants. In the case of an adult, there is no problem when using an airbag, but in the case of a small child, a deployed airbag may act as a dangerous factor that threatens the life thereof. Therefore, whether an airbag for a passenger seat is to be deployed must be determined differently depending on the type of vehicle occupant. For this determination, a variety of research on and development of a vehicle occupant classification apparatus for classifying a vehicle occupant sitting in a seat have been actively conducted.
A vehicle occupant classification apparatus, which is generally used at the present time, basically classifies an adult and a child by measuring the weight of an occupant sitting in a seat, and additionally considers the shape of the hip of an occupant. However, as shown in FIG. 1, in such a conventional vehicle occupant classification apparatus, since the difference between the weights of an occupant, measured by a sensor according to the variation in the posture of the occupant, is large, errors frequently occur in classifying an occupant.
Further, the conventional vehicle occupant classification apparatus is problematic in that, since a hard plastic mat, having a sensor therein, must be installed under a seat cover, or, alternatively, a separate structure must be installed in the seat, the plastic mat or separate structure acts as a factor that limits the design of seats.
Accordingly, a new system for classifying a vehicle occupant is proposed in Korean Pat. Appln. No. 2007-0067276 (filed on Jul. 4, 2007). This system is constructed to measure variation in the amount of charge attributable to an occupant sitting in a seat, that is, current variation, and to determine whether an occupant is seated and which type of occupant is sitting, using the current variation. The measurement of current variation is performed using the principles in which the capacitance formed between a vehicle body and a conductor installed under a seat cover varies according to the permittivity of an occupant sitting in the seat and in which the amount of charge varies according to the variation in capacitance.
However, as shown in FIG. 2, in the vehicle occupant classification system, when moisture permeates into the seat, errors may occur in the classification of occupants. Since moisture has high permittivity and relatively low resistance, the current value measured by the sensor in the seat increases when moisture permeates into the seat. Therefore, even if an occupant is a small child, the current value increases due to the moisture (that is, above a threshold value), and thus there is the probability of the occupant being erroneously determined to be an adult and an airbag being deployed.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known to a person skilled in the art.